And even though it's not entirely clear how close to fluent Timothy Doner is in any of his studied languages, the high school sophomore -- along with other polyglots like him -- are certainly different from most Americans, who speak one or maybe two languages.

That raises the question: Is there something unique about certain brains, which allows some people to speak and understand so many more languages than the rest of us?

The answer, experts say, seems to be yes, no and it's complicated. For some people, genes may prime the brain to be good at language learning, according to some new research. And studies are just starting to pinpoint a few brain regions that are extra-large or extra-efficient in people who excel at languages.

For others, though, it's more a matter of being determined and motivated enough to put in the hours and hard work necessary to learn new ways of communicating.

"Kids do well in what they like," said Michael Paradis, a neurolinguist at McGill University in Montreal, who compared language learning to piano, sports or anything else that requires discipline. "Kids who love math do well in math. He loves languages and is doing well in languages."

"This is just an extreme case of a general principle," he added. "If you practice and have a great deal of motivation for a particular domain, you're going to be able to improve in that domain beyond normal limits."

Very young children are remarkably good at learning multiple languages simultaneously. They can develop native-sounding accents in each tongue. And into adulthood, all reinforced languages hold their own in the brain without interfering with the others -- unlike later learners who may have trouble remembering a second language when they begin to learn a third.

With age, though, it not only becomes tougher to learn new languages, there may even be developmental stages beyond which certain nuances of language simply become inaccessible. By the age of 9 to 12 months, for example, babies begin to lose the ability to distinguish between sounds that are not used in their native language, said Loraine Obler, a neurolinguist at the CUNY Graduate Center in New York.

After about age 4, most people will never gain a truly deep grasp on a second language's morphology, which refers to the rules that govern how words are formed from linguistic units. After age 7 or so, the brain begins to pay more attention to what it's learning, Paradis said, which affects the type of memory kids use to pick up languages.

And beyond puberty, it becomes unlikely that someone will be able to speak a new language without a foreign accent, though Doner is unique in how impressive his accent sounds, which may reflect a late-to-mature brain. (There seems to be no cut-off point for learning vocabulary).

For more than a century, scientists have known that there are key areas on the exterior cortex of the brain's left hemisphere, known as Broca's area and Wernicke's area, that are critical for learning to speak and understanding speech, Obler said. There are also many other areas throughout the brain that process language.

Genes, neurotransmitters and brain regions involved in long-term memory play roles as well, Paradis said. And a number of different structures probably come into play when people speak a second language compared to when they speak their first.

That would explain why brain damage from Parkinson's, Alzheimer's or other disorders that affect specific areas of the brain can knock out just a native language -- or just a language that was learned later in life, leaving the other one intact. Aging can also bring out an accent that was once unnoticeable.

Only in the last few years have scientists begun to zero in on brain regions that seem to matter most in helping polyglots develop their impressive skills.

In a 2008 study in the journal Cerebral Cortex, for example, researchers found better language learning abilities in college students with a larger Heschl's gyrus, an area on the left side of the brain that processes pitch. But that finding only applies to learning tonal languages like Mandarin, said study author Patrick Wong, a neuroscientist at Northwestern University in Evanston, Illinois.

In another study, published last year in the Journal of Neuroscience, Wong's group found that good language learners had stronger connectivity in the white matter of the auditory cortex, which is part of the language network. And in studies currently in press, the team will announce better efficiency in connections between neurons as well as a genetic component to the whole system.

And it's not just polyglots who are providing clues, Obler added. In her research on people who struggle with new languages, she has found parallels with dyslexia.

Yet, even as research reveals biological clues in the brains of polyglots or their opposites, we are probably not completely fated to either excel or fail at languages. Our biology may simply determine which strategy we should use to learn new dialects.

"You're not doomed just because your Heschl's gyrus is small," Wong said. "The goal in our research program is to find predictors. And once we find predictors, we can put people into the right kind of training program."

But the field of neurolinguistics is still new. So for now, the process of language learning in the brain remains full of secrets.

As Obler said, someone once "wanted to know how to make the brains of merely normal learners as good as excellent learners. I said, 'I'm not going to be able to answer that for decades.'"